The present invention is directed towards an improved eye tracking apparatus, and in particular an eye tracking apparatus for use on an auto stereoscopic viewing system.
The present Applicant""s original 3-D auto stereoscopic display unit included an eye tracking unit to enable the correct positioning of a stereoscopic projector pair, to thereby enable the observer to view 3-D video without the use of special glasses. This tracking system, which was disclosed in Australian Application No. 42929/96, required the data for the location of eyes in the x and y directions. That is, the horizontal and the vertical positions of the eyes from a known datum point at a set distance from the single camera.
The earlier developments were based on the premise that the viewer would be located a relative fixed distance from the screen. However, it is now desirable to develop a system which is able to determine the location of the eyes in the x, y and z directions. That is, the horizontal (lateral) position, vertical (height) position and horizontal (depth) position from a known datum point. Such a system will enable an observer to move left and right, up and down, and also forwards and backwards with respect to the screen. However, to create such a system additional data is required in order to obtain the depth or z information.
The present applicants have investigated a number of alternative systems using feed back focus information and ultrasonics. However these other methods have not been found to be technically or commercially practical at this time.
It is therefore the object of the present invention to provide an eye tracking system which is capable of providing the location of the observer""s eyes in the x, y and z directions.
It is also intended that the observer should not be required to wear any specific head-gear and the system should track the observer reliably irrespective of any corrective glasses worn by the observer. Preferably, the system should correctly report the observer""s eye position during momentary blinking or periods where one or both of the observer""s eyes are closed or the viewer has momentarily looked away from the system. Ideally, it is also intended that the system should reliably differentiate between the observer""s eyes and other facial features e.g., earrings or background objects.
With the above object in mind the present invention provides in one aspect a tracking system for locating the head and/or eyes of a viewer including an illumination means; a plurality of cameras; and a processing means; wherein at least one of the viewer""s eyes is illuminated by the illumination means to enable capture by each camera, and said processing means is adapted to process images from each camera so as to detect the position of the viewer""s eyes and/or head.
For a system that is required to track in the z direction as well as x and y then preferably two cameras can be located on either side of the observers head or the autostereoscopic display system that requires the coordinates of the observer to be determined. The processing means is then able to utilize a method of triangulation to locate the viewer""s head and/or eyes. In order to obtain a more compact tracking system, each camera can be associated with a corresponding mirror ideally located at 135 relative to the optical axis of each respective camera. The addition of such mirrors does not adversely affect the performance of each camera, but do allow for a more compact system.
Ideally, the illumination means can be formed from a plurality of separate illumination means, each separate illumination means being moveable in response to movement of the viewer.
It will be understood that such illumination means will conform to local safety regulations.
In a further aspect the present invention provides a tracking tower for locating the eyes of a viewer including:
an illumination means for illuminating at least the eyes of a viewer;
a vertically mounted camera for capturing at least the reflected light from the eyes of the viewer; and
a mirror positioned to enable the vertically mounted camera to capture images in front of the tracking tower.
In yet a further aspect the present invention provides a method of tracking the eyes of a viewer including:
projecting light capable of being reflected from the cornea of a viewer from an illumination means onto the eyes of the viewer;
capturing the image of the viewer by a plurality of cameras capable of detecting the reflected light from the viewer""s cornea;
and processing the captured images from each camera in a processing means to determine the position of the viewer""s eyes.
In another aspect the present invention provides an autostereoscopic display system including:
a display means for displaying images to be viewed by a viewer;
a tracking tower located on either side of the display means, each tracking tower including:
an upper and lower illumination means for illuminating at least the eyes of a viewer;
a vertically mounted camera for capturing at least the reflected light from the eyes of the viewer; and
a mirror positioned to enable the vertically mounted camera to capture images of the viewer in front of the tracking tower;
a processing means located below the display means for receiving the images captured by each camera, determining the position of the viewers eyes, and sending the output from the processing means to each tracking tower to thereby adjust each said camera in response to movement of the viewer;
and wherein the output from the processing means is utilized to display respective left and right eye images of the image to be viewed by the viewer on the display means.